Electric lock plug



Jan. 8, 1957 L. SEPULVEDA 2,777,023

ELECTRIC LOCK PLUG Filed Feb. 12, 195-6 INVENTOR. Louls- SEPULVEDA ELECTRIC LOCK PLUG Louis Sepulveda, New York, N. Y.

Application February '12, 1954, Serial No. 409,897

3 Claims. (Cl. 200 -42) This invention relates to electric plugs and, more particularly, has reference to a plug of the type used on the cord of a television or radio receiver, electric iron, or other household appliance.

The main object of the present invention is to provide an improved electric plug of the type equipped with a switch, it being proposed, in carrying out the invention, to so design the switch of the plug as to prevent use of the television set or household appliance without first inserting a specially shaped key and rotating the key in the plug to a position in which the switch of the plug is closed.

In this way, it becomes possible to prevent children or other unauthorized individuals from turning on a television set or using some household appliance, since the switch equipped plug is so designed as to necessarily require that a key of a special shape be utilized therein, before electrical power canflow through the plug.

A further important object of the present invention is to provide a plug of the type stated which will be so designed as to permit the manufacture thereof at a realtively low cost, the plug being provided with interfitting parts capable of assembly with minimum difliculty, the individual parts making up the complete structure being formed readily from inexpensive material.

A further object of importance is to provide a plug of the type stated which will be safe in use, the plug being equipped with a switch having a rotatable center piece of insulating material, the construction being specifically designed to prevent contact between the inserted key and the conductive portions of the plug. The construction is further designed, in this regard, to prevent insertion of :a wire, pin, or other object by a child under circumstances which might result in the contacting of a conductive part of the structure by said pin or other inserted object.

Still another object of the present invention is to provide a plug of the type stated which will be compact, attractive, and specifically designed to facilitate insertion of the specially formed key.

For further comprehension of the invention, and of the objects and advantages thereof, reference will be had to the following description and accompanying drawings, and to the appended claims in which the various novel features of the invention are more particularly set forth.

In the accompanying drawings forming a material part of this disclosure:

Fig. l is a prospective view of an electrical plug formed in accordance with the present invention, the key being shown in position for insertion into the plug.

Fig. 2 is a plan view of the plug with the cover section removed, the full lines showing the switch components in circuit closing position, and the dotted lines showing said components in position to break the circuit.

Fig. 3 is a longtiudinal sectional view taken substantially on line 33 of Fig. 1.

Fig. 4 is an exploded perspective view of the component parts of the switch assembly.

nited States Patent Fig. 5 is a plan view of the switch block per se.

Fig. 6 is a plan view of the base section of the plug, per se.

Referring to the drawings in detail, the reference numeral 10 has been applied generally to the base section of the plug constituting the present invention. The reference numeral 12 has been generally applied to a cover section complementing the base section. A switch support block 14 is engaged between the sections, and carries :a switch assembly designated generally by the reference numeral 16, said switch assembly being operated by insertion and rotatable movement of a specially shaped key 18.

Considering first the construction of the base section 10, this is formed from a single piece of electrically insulative materials such as plastic or the like, molded to a shape shown to particular advantage in Fig. 6. The base section 10, on its inner face, is formed with a large, substantially centrally disposed, shallow recess 20, said recess being in communication at one end of the base section with parallel, transversely spaced grooves 22, 24.

Seated in the grooves 22, 24 are conductive prongs 26, 28 respectively, said prongs being adapted for insertion in a conventional receptacle or socket, not shown.

The prong 26, as best shown in Fig. 2, has an arcuately shaped midlength portion 30 which extends in contact with a complementarily shaped side wall of the recess 20. The midlength portion 30, within the body of the plug, is formed with an ear 32, said ear 32 being integral with the curved portion of prong 26, at the inner end of said prong.

Prong 28, within the body of the plug, has an offset or reversely bent portion 34 merging into an arcuately shaped inner end portion 36 lying within the recess 20 of section 10.

The curved inner end portion 36 is disposed diametrically opposite a complementarily curved inner end portion 38 of a terminal 40, the terminal 40 being reversely bent intermediate its ends and being provided, at that end thereof remote from the portion 38, with an car 42 spaced transversely from the ear 32, within the body of the plug, ears 32 and 42 being adapted to receive the hated ends of the wires of an electric cord 46 extending to a television set, radio set, or electrical household appliance.

Referring now to Fig. 5, the switch assembly support block 14 is formed with a center recess 47, said recess being provided with diametrically opposite depressions 48 in its side wall, the depressions 48 being eccentric to the center point of the recss 47, and terminating at one end in abutments, for a purpose to be made presently apparent. As shown in Fig. 5, slots or grooves 50, 52 are formed in the block 14, said slots extending to one side of the block and being in communication with the recess 47. The slots or grooves 50, 52 are adapted to receive the prong 28 and terminal 40 (see Fig. 2), the curved inner ends of said prong and terminal being seated within the depressions 48 of recess 47.

Also formed in the side wall of the recess 47, at diametrically opposite locations in said recess, are depressions 54, said depressions 54 extending at locations in the side wall of the recess intervening between the depressions 48. 'Depressions 54, like the depressions 48, extend eccentrically to the center of the recess 47, and terminate at one end in abutments analogous to the abutments of the depressions 48.

A center opening 56 is formed in the recess47, and is adapted to receive the lower end portion of a cylindrically shaped switch element '58. Element 58 is rotatably mounted within the opening 56, and as shown to advantage in Fig. 4 is formed with a diametrically extending slot 60 at its lower end. Slot 60 is adapted to receive the straight midlength portion 62 of a movable bridging element having oppositely extended, curved ends 64.

At its upper end, the rotatable switch element 58 is integrally formed with a projection 66 of noncircular cross-section, the projection 66 being reduced in size relative to the main body of the switch element.

A key is adapted to engage the projection 66, and is thus shaped complementarily to said projection. The key 18 illustrated in the drawing, accordingly, has a tubular shank 68 shaped to engage the projection 66 for the purpose of rotating the switch element 58 when the circuit through the plug is to be opened or closed, as the case may be.

The key can be formed from a single blank of sheet metal material, as shown in Fig. 1, with said blank being meant to provide the tubular shank 68 at one end of the key, and a handle 70 at the other end of the key.

As shown in Fig. 2, when the key is inserted in the plug and engaged with the projection 66, and then rotated 90 in the direction shown by the arrow in Fig. 2, the contact member carried by the switch element 58 will be rotated to a corresponding extent. Thus, in Fig. 2 the contact member is shown in full lines in position to bridge the curved terminals 36, 38, and in this position of the parts, electrical current can flow to the particular appliance on the cord of which the plug is mounted.

Continued rotation of the key in the same direction through an additional 90 will serve to adjust the contact member of the switch assembly to the dotted line position shown in Fig. 2. In this position, the curved ends 64 will engage in the diametrically opposite depres sions 54 of recess 47.

Reverse rotation of the switch assembly is prevented by the abutments at one end of each of the depressions 48, 54.

The cover section 12 is formed, on its inner face, with a recess 72 complementing the recess 20 of the section 10, to receive the top face of the block 14 (see Fig. 3). Also formed in the cover section is a center opening 74, said opening being provided for insertion of the key 18. The outer face of the section 12 is provided with an annular lip 76 surrounding the opening 74, so as to insure that the noncircular projection 66 will be recessed within the plug to an extent sufficient to prevent grasping thereof by a child or other unauthorized individual.

The sections and 17. are, of course, secured together in any suitable manner, and in the illustrated embodiment are formed with registering, countersunk openings D receiving screws 78, said screws being provided with nuts for the purpose of tightly connecting the sections 10, 12.

it is to be noted that at its inner end, the opening 74 is counterbored to a slight extent to define a shoulder extending about the same, which shoulder will engage the marginal portion of the upper end of the cylindrical switch element 58 for the purpose of holding said switch clement against dropping accidentally out of the opening 74.

The construction illustrated and described herein has the advantage of being adapted for facilitating manufacturing operations. For example, in assembling the de vice, the switch support block is first inserted in the recess of the section 10, after which the prongs are positioned as shown in Fig. 2, the block being adapted to cooperate with the sections 10, 12 in holding the prongs in place. Further, the block is adapted to receive the inner end of the terminal 40, to hold said inner end of the terminal in proper position Within the recess 47 of block 14.

Thereafter, the S-shaped contact member of the switch assembly is inserted in the slot 60, and the lower end of the switch element 58 is positioned Within the opening 56 of the block 14. Positioning of the element 58 in said opening 56 serves to hold the contact member 62 4 within the slot 60, at the inner end of said slot, as will be readily apparent from a study of Fig. 3.

Thereafter, it is merely necessary that the cord be connected electrically to prong 26 and terminal 40, after which the cover section is applied. Application of the cover section will serve to hold the switch element 58 in place, as will be readily apparent.

In use, it is merely necessary that the key 18 be rotated for the purpose of opening or closing the switch provided in the plug, to control use of the appliance.

While I have illustrated and described the preferred embodiment of my invention, it is to be understood that I do not limit myself to the precise construction herein disclosed and the right is reserved to all changes and modifications coming within the scope of the invention as defined in the appended claims.

Having thus described my invention, what I claim as new, and desire to secure by United States Letters Patent 1. A lock equipped electrical plug comprising a plug body, a pair of prongs extending therefrom, a terminal mounted within said body in spaced relation to the prongs, one of. the prongs and said terminal being adapted for connection to the wires of an electrical cord, a rotatable switch assembly mounted within said body between the terminal and the other prong and including a rotary switch element and a contact member carried by said element, said contact member being adapted to bridge the terminal and the other prong in one position to which the switch assembly is rotated, means supporting the switch assembly within the body for rotation, and means insertable into the body for rotating the switch assembly, the contact member being formed as a length of conductive spring material having laterally extending end portions engaging the terminal and said other prong in said position of the contact member, the terminal and said other prong having curved ends disposed within the body and said end portion being curved complementarily to said curved ends to engage thereagainst.

2. A lock equipped electrical plug comprising a plug body, a pair of prongs extending therefrom, a terminal mounted within said body in spaced relation to the prongs, one of the prongs and said terminal being adapted for connection to the wires of an electrical cord, a rotatable switch assembly mounted within said body between the terminal and the other prong and including a rotary switch element and a contact member carried by said element, said contact member being adapted to bridge the terminal and the other prong in one position to which the switch assembly is rotated, means supporting the switch assembly within the body for rotation, and means insertable into the body for rotating the switch assembly. the switch element including a projection of noncircular cross section and said second-named means having a part mating with the projection for joint rotation of the element and second-named means, the second-named means being formed as a key having a tubular shank of ncncircular cross-section defining said part of the second-named means and receiving said projection, the body of the plug having an aperture through which the key is insertable into engagement with the projection, the projection being recessed within the aperture, said switch element including a Z-shaped bridging element, the ends thereof being curved.

3. The combination of claim 2, wherein said switch includes a circular body portion and a slot extending into said body portion, the midlength portion of said switch bridging element being seated in said recess.

References Cited in the file of this patent UNITED STATES PATENTS 1,684,148 Ronneberger Sept. 11, 1928 1,903,586 Arnold et al. Apr. 11, 1933 2,217,585 Yates Oct. 8, 1940 2,644,864 Childs July 7, 1953 

